Coupling device for high-frequency apparatus



y 1948. J. '5 DONAL, JR., Er AL 2,442,118

COUPLING DEVICE FOR HIGH-FREQUENCY APPARATUS- Filed July 29, 1943 m. l .M -Q

INVENTORS' & JOHN S.DONRL JR. 8 HOLDHRDKHEGBRR @wmw ATTORNEY I ///l Ill/IV Patented May 25, 1948 COUPLING DEVICE FOEHIGHJREQUENCY APPARATUS Johns. Donal, J1'., and Howard R. Hegliai, Princeton, N. J., assignors to Radio Corporation of America, a corporation'- ofDelaware Application July 29, 1943, SerialiNo; 49.6;570

7 12 Claims. 1

Our invention relates-to coupling means for? ultra high frequency electronic apparatus and more pjarticularlyto coupling-means useful in coupling evacuated envelopes such as electron discha'rge devices utilizing: cavity. resonators, wave guides; coaxial lines and-other like circuit element'swithe'ach other, or as a radiator for an L evacuated cavity resonator. or the'like.

- Cduplin'g-means-for coupling evacuated hollow conducting elements, such as cavity resonators utilized with electron discharge devices; with other cavityresonators, waveguides and coaxial lines; do not lend themselves readily tomachine made mass production. The assembly of transmitti'ng or receiving type tubes using cavity resonators-or metal" envelopes presents considerable dlficultiessince in the usual'coupling device, such as the coaxial line, the central-conductor must be installed'in a late stage ofthe assembly. The

central conductor must be sealed through the me'tal envelop'e of the tube'or the resonator to maintain the vacuum within the electron discharge device; This requires careful sealing and may barthe use of material for the conductor having the optimum characteristics for high frequency conductivity. If it is desired'to make the outer conductor of the coaxial line of material having poor radio frequency conductivity, it is common tosilver-plate or'otherwise'treat the innersurface of the outer tubular conductor to increase it's r'a'dio frequency conductivity. With the central conductor sealed-in this becomes a difiicu'lt process. Where high voltages are utilized c'or'ona-lossesoccur at the tipof the inner conduct'or when this inner conductor is utilizedas 'c'ou'pled to the coaxial line must' be prevented. Extendingthe coaxial line directly within the waveguide does not provide a juncture at which the impedance of the coaxial line and the impeclance of the waveguide or resonator are matched; thus causingreflection. The problem is'made-more pressing when it is desired to bias the coaxial line and the waveguide *or resonator coupled thereto at different voltages since this requires'spacing; betweenthe waveguide and coaxial line or resonatorand-provides another cause or source, of; radio frequencyi losses through:- the space between theqcoupled elements;

It is, therefore, an. object of. our invention-to provide an improved c ouplingde'vice for coupling evacuated: hollow conducting members We waveguide or cavity resonator;

It is another object of our: invention-to provide such. a' device Which facilitates, machine-made mass production.

A further object of'our inventionis to provide such. adevice whichwill greatly facilitate the manufacture and assembly. of transmitting" and. receivingtubes utilizing cavityresonators or metal envelopes.

Astill further object ofour invention is to eliminate; the seals between the centralFcIonductor and the outer conductor of; af coaxial lineused; asa o plin device. as has. en. required-in. t e pa Afurther object of our invention'is to provide such adevice, inwhich" treatment of} the inner surfacesof the outer conductor of thecoaxial line for improvin -its, ra iof equ n y ar cteris ics is facilitated.-

Another object of our; invention is toprovide uc qa ia l ne co pling e ce'in. w ich the corona -1ossesfrom the inner conductor are minimized siu r b e owf our i ventionis o e u h a co pling d v ce w i h rovides; n easy and exact electricalconnection and which may be rigidly connected to the Waveguide or resonator; v.

Another object of our invention is toprovide mechanical protection to minimize breakage of the, elasseparts ofthe enve ope and coup in de- V108;

The-novel-features;which we believe tape-chareq er s i -q u ve itiq a e se f new.- ticularity; in the appended; claims; but the-inventionitself will-bestbe understood by reference to the following description en inrconnection'with e c m eny ne-drawih in h h i u e 115 a coupling device madeaccording to our invention a oc ted w h ai ct o scharge; v ce-ha ing a metal v e e; ahdaw v eui a shown p rt ally in secti n; Fi ure" is an la ed view wi a s of t e c s r c i n .o -the; t rnation. of th -coax alHhe ouplin -d i e s own nF ue '1'; and i ure 3 s a mod fica ion o the device: shown i Fi ure zrfor perm ttin voltage d fi r ntials be ween dif rent pe cm of heap aatu u edin r vinn:nt n:

nF sure qu lins' d v cem d a cordin to ourinvention is-used to couple a-magnetron within an evacuated envelope to a waveguide. Themagnetron includes the evacuated metallic envelope having exhaust tube II and containing the magnetron anode block l2 provided with a plurality of radially directed anode segment elements I3, the space between each of the elements I3 providing in effect a cavity resonator. Positioned axially of the magnetron is an indirectly heated cathode [4 provided with leads [5 and I6 extending through the shield l1 terminated by insulating cup member I8 through which the leads are sealed. The means for applying a magnetic field are not shown, but provide a field parallel to the cathode and between the cathode and the anode segments.

In accordance with our invention we provide a coupling device comprising a, coaxial line having an outer hollow conductor 20 closed at one end by means of the cone-shaped insulating cap member 2|. The outer conductor 20 is sealed to the envelope I0 and extends within an opening provided for it in' the magnetron anode 12. An inner conductor 22 is positioned coaxially of the outer conductor 20 and abuts the inner wall of the cone-shaped insulating cap 2| near the tip but is not sealed thereto. The other end of the inner conductor 22 is provided with coupling loop 23,.one end of which is-connected to the ring member 23'. We provide a, cup-shaped member 24 having lip or flange 24 which rigidly supports the coaxial coupling line on the waveguide 25 having an opening26 through which the inner coaxial member extends, the inner end of the coaxial member extending at least one-quarter wavelength beyond the outer conductor 20 and within the waveguide to generate an-electromagnetic field in response to excitation of the coaxial line by the magnetron.

In order'to provide an exact electrical connection between the waveguide and the coupling member, the cup-shaped member 24 is spaced fron 'i'the outer conductor 20 for a distance equal to a half wavelength of the generated radio frequency voltages. This in effect provides a zero impedance between the inner end of the cupshaped member adjacent the aperture and the outer conductor 20 so that in effect theresult is as if the end of the outer conductor were connected directly to the'waveguide 25 so far as electrical conditions are concerned, The lip 24' may be directly connected to the outer surface of the waveguide 25.

This form of device permits thecoupling of an evacuated container which may be a cavity resonator or an'electron discharge device such as described. A device made according to our invention is readilyproduced by a mass process since allparts may be made exactly to measure prior to assembly. Because of the independence of the 'innerand outer conductors, and because no sealing is required between the inner and'outer conductors, the coupling device'may be quickly assembled. Seals between the inner and outer conductors are eliminated, thus reducing the likelihood of leaks and simplifying construction. Because the inner conductor may be easily removed, treatment of the inner surface of the outer conductor for improving the radio frequency impedance is great facilitated. Because of the construction of the insulating cap and because-the inner conductor does not extend through the cap the corona losses from the inner conductor are surface of the glass where the electrical field is less than at the surface of the conductor which has a smaller radius of curvature than does the glass sheath. Because of the formation of the supporting cup 24, the impedance between waveguide and coupling member may be reduced to a minimum while at the same time it serves to protect the seal of the cap 2| to the outer conductor Figure 2 is an enlarged view of the construction of the end of the coupling line and its method of support in the waveguide '25. The dimension a of Figure 1 is of importance whereas that of b, the lip, is not critical in the arrangement shown in Figures 1 and 2. As pointed out above dimension a is equal to a half wavelength of the generated radio frequency voltages.

Should it be desirable to maintain the waveguide and the'tube envelope at two different potentials, our invention may assume the form shown in Figure 3. Positioned between the lip or in order to prevent radiation throughthis space it is necessary to make. dimension 1) effectively equal to a quarter wavelength,,taking into consideration the kind of insulation used. Dimension a is again one-half wavelength. This in effect is comparable to a quarter wave openatransmission line so that the impedance between'lip 24' and the waveguide at its inner edge will be zero or substantially zero so 'thatin effect this part of the cap is short circuited to the waveguide. V V

While we have indicated the preferred embodiments of our invention of which we are now aware and have also indicated onlyone specific application for which our invention maybeemployed, it will be apparent that our invention is. by no means limited to the exact forms illustrated .Or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing fromthe scope of our invention as set forth in the appended claims: s

What we claim as newis:

l. A coupling means for ultra high frequency evacuated devices including a coaxial line having an outer tubular. conducting member, a cup-'- shaped element of insulating material sealed to one end of the tubular conducting member and extending outwardly therefrom, and an inner conductor coaxial with said outer tubular'conducting member and extending outwardly past the end of said; outer tubular conducting member with its end contacting the inner surface of the cup-shaped element,-the other end of said inner conductor terminating in a. loop electrically connected to the outer tubular conductingmember, said inner conductor being supported only at its ends. 2. A first evacuatedh ollow conducting body resonant at ultra highifrequencies, a 1 coupling means for coupling the evacuatedfhollow conducting body to asecond' hollow conducting body and includingva coaxial line having anouter tubular conducting, member,- 7 a substantially cone-shaped element of insulatingr'material sealed to one end of the tubular conducting member and extending :outwardly therefrom; anda conductor coaxial with said outer tubular :conducting member and extending outwardly past the endof said outer tubularv conducting member with'its end'contacting' the inner surface of the cone shap'ed element at'the' peak thereof, the

a ira irs openend of the outer tubularconductinglmem- -bercommunicatingwiththe first hollow conducting body, the other 'endbf saidinner conductor terminating in a loopelectrically connected to-the'outer tubular conducting member.

3. A couplingmeans for ultra highfrequency evacuated devices including a coaxial line having an outer tubular conducting xmember, a cupsupported only at its ends, and a conducting cupshaped-member surrounding the end-of said outer tubular conducting member which is sealed to the cup-shaped element of insulating material and spaced from the outer tubular conducting member and connected to said outer tubular con" ducting member at a point spaced from the sealed end thereof. Y

4. An evacuated hollow conducting body reson-ant at ultra high frequencies, a coupling means for said body includinga' coaxial line having an outertubular conducting member, a cup-shaped element of insulating material sealed to one end of the outer tubular conducting member and extending outwardly therefrom and an-inner conduct-or coaxial with said outer tubular conducting i'nember and extending outwardly past the end of said outer tubular conducting member with its end within the cup-shaped element, anda conducting cup-shaped member surrounding the end of said outer tubular conducting member which is sealed to the cup-shaped element of insulating material and spaced from the outer tubular conducting member -for a length equal to a half wavelength of the operating frequency of the device to which the coupling means is coupled and connected to said outer tubular conducting member, the open end of said coupling means communicating with the interior of the evacuated hollow conducting body, and the open end of said cup-shaped member being adjacent said cupshaped element of insulating material.

5. A coupling means for ultra high frequency evacuated devices including a coaxial line having an outer tubular conducting member, a cupshaped element of insulating material sealed to oneend of the outer tubular conducting member and extending outwardly therefrom and an inner conductor coaxial with said outer tubular conducting member and extending outwardly'past the end of saidouter tubular conducting member and its end contactingtheinnersurface. of the cup-shaped element, a conducting cup-shaped member surrounding the end of said outer tubular conducting member which is sealed to the cupshaped element of insulating material, the walls of said end cup-shaped member being spaced from the outer tubular member and connected to said outer tubular conducting member, a hollow conducting member, having an aperture therein, the end of the coaxial line having the cup-shaped element of insulating material extending within said aperture, a flange on said cup-shaped member fixed to said hollow conducting member, and an insulator between said flange and said hollow conducting member.

6, An evacuated cavity resonator, means for exciting said resonator, and means for coupling said resonator to a radiator and-including a coaxial linehaving an outer tubular member connected tosaid resonator-and communicatingwith the interior thereof, an insulating cap sealed at the outer endof said-hollow tubular member, and

'aninner conductor coaxial withsaid outer-tubular member and having a loop on one end within said-cavity -resonator,- the other end of said inner conductor extending past the -end of the outer tubular-member and contacting the inside fOf said insulating cap, said inner conductor being supportedonly at ii /sends.

' =7, A-coupling means for ultra high frequency evacuated devices including acoaxial line having an ;-outer tubular conductingmember, a cupshaped element "of insulating material sealed to one end oft'hje-outertubular conductingmember and extending outwardly therefrom' and an'inner conductor coaxial with said outer tubular conducing member and extending outwardly past the end of said outer tubular con-ducting member with itsend within the cup-shaped element, and

a conducting cup-shaped member surrounding bein jnrov ded Wit a a i l y ir cted lan for 'sec' rin'eisa d c u lin m n to aholl c ducti g body.

QB- An evacuated hollow .jcon uctins body I adapted to be excitedat ultra high frequencies, a

c up in eanso saidb y in ludingal oax line having an; outer tubular conducting ,rnember,

a cup-shaped element of insulating material sealed toone end of the outer tubular conducting member and extending outwardly therefrom and an inner conductor coaxial with said outerwtubular. conducting member and,extend-ing. outwardly past ,the''- end of said outer tubularQconducting member withits end contactingthe interior surface of the cup-shaped element, a conducting cup-shaped member surrounding the cadet said outer tubular conducting-member which is sealed .to'the cup-shaped-element of, insulating material and having its side walls spaced from the outer tubular conducting member ,and connected to said outer tubular conducting-member at a point whichisspaced from-thesealed end thereot, the

open end of said coupling means-communicating with the interior of th evacuated hollow conduc n -;b. iv. and a econd q ow n uc in body ari ea a e u e he d ofai cou ling means provided with the cup-shaped, element, I of insulating material extending within said second hollow conducting body through said aperture, the open end of said cup-shaped member having a flange securing said coupling means to said second hollow conducting member.

9. An evacuated hollow conducting body adapted to be excited at ultra high frequencies, a coupling means for said body including a coaxial line having an outer tubular conducting member, a cup-shaped element of insulating material sealed to one end of the outer tubular conducting member and extending outwardly therefrom and an inner conductor coaxial with said outer tubular conducting member and extending outwardly past the end of said outer tubular cone ducting member with its. end contacting the interior surface of thecup-shaped element, aconducting cup-shaped member surrounding the end eating with the interior of the evacuated hollow' conducting a body, a second hollow conducting body having an aperture, the end of said couplin means provided with the cup sha ped element, of insulating material extending within said second hollow'conducting body through said aperture, the open end of said cup-shaped member having a flange securing said coupling means to said second hollow conducting member, and insulating means between the flange and said second hollow conducting member for permitting different.

direct voltages on said coupling means and said second hollow conducting member. I

' 10. An evacuated hollow conducting body resonant at high frequencies, a coupling means for said body including a coaxial line having an outertubular conducting member, a cup-shaped element of insulating material sealed to one end of the outer tubular conducting member and extending outwardly therefrom and an inner conductor coaxial with said outer tubular conducting member and extending outwardly past the end of said outer tubular conducting member with its end extending Within the cup-shaped element, a conducting'cup-shaped member surrounding the end of the outer tubular conducting member which is sealed to the cup-shaped element of insulating material and having its side walls spaced from the outer tubular conducting member and connected to said outer tubular conducting member at a point which is spaced from the sealed end thereof, the open end of said coupling means communicating with the interior of the evacuated hollow conducting body, and a second hollow conducting body having an aperture, the cup-shaped element extending within said aperture, said cup-shaped conducting member being secured to said second hollow conducting body. v

l 1. A coupling means for an ultra high frequency evacuated device including a coaxial line having an'outer tubular conducting member, a cup-shaped element of insulating material sealed to one end of the outer tubular conducting member and extending outwardly therefrom and an'inner conductor coaxial with said outer tubular conducting member and extending outwardly past the end of said outer tubular conducting member with its end within the cup-shaped element, a conducting cup-shaped member surfile of this patent? I rounding the end of said outer tubular, conducting' member which is sealed to thecup-shaped element of insulating material and having its side walls spaced from the outer tubular member and connected to said outer tubular conducting member, a hollow conducting member having an aperture therein, the end of the coaxial line supporting the cup-shaped element of insulating material extending within said aperture, a flange on said cup-shaped member fixed to said hollow conducting member, and an insulator between said flange and said hollow conducting member, said flange having a radial dimension equal to substantially a quarter wavelength of the operating frequency of the ultra high frequency evacuated device. I a n j 12. A coupling means for an ultra high frequency evacuated device including a coaxial line having an outer tubular conducting member, a

cup-shaped element of insulating material sealed to one end of the outertubular conducting member and extending outwardl therefrom and an inner conductor coaxial with said outer tubular conducting member and extending outwardly past the end of said outer tubular conducting member with its end within the cup-shaped element, a conducting cup-shaped member surrounding the end of said outer tubular conducting member which is sealed to the cup-shaped element of insulating material and having its side walls spaced from the outer tubular member a distance equal to a half wavelength of the operating frequency of the ultra high frequency evacuated device and connected to said outer tubular conducting member, a hollow conducting member having an aperture therein, the end of the coaxial line supporting the cup-shaped element of'insulating material extending within said aperture, a flange on said cup-shaped member fixed to said hollow conducting member, and an-insulator between said flange and said 11011DW conducting member, said flange having a radial dimension equalto'substantiallya quarter wavelength of the operating frequency of the ultra high'frequency evacuated device.

REFERENCES CITED The following references are of record in'the UNITED STATES PATENTS Number Name Date 2,128,234 Dallenbach i Aug. 30, 1933 2,311,520 Clifiord Feb 16, 1943 2,351,895 Allerding 'June 20, 1944 2,404,086 okress July '16,, 1946 

